Process and apparatus for crimping yarns and product made thereby

ABSTRACT

A PROCESS AND APPARATUS FOR FEEDING A PLURALITY OF STRANDS AT CONSTANT SPEED THROUGH TWISTER MEANS HAVING A PLURALITY OF GUIDE ASSEMBLIES SPACED APART SYMMETRICALLY ABOUT A CIRCLE AND WHEREIN THE STRANDS ENTER AND LEAVE THE GUIDE ASSEMBLIES AT EQUAL ANGLES.

y' Jan. 12,1971- Fnq sept, s. l1962sv a. M.Mc|NTosH 3,553,952 PROCESS AND APPARATUS FOR CRIMPING YARNS Al y PRODUCT MADE THEREBY 2 Sheets-Sheet 1 ,Mvfm

Jan. 1251971 s. M. Mcm-rasa 3,553,952 PROCESS AND APPARATUS .FOR CRIMPING YAHNSl AND Y vPxzolmc'r MADE THEREBY Y y y i MWZa/e/w-VSM U.S. Cl. 57--34 8 Claims ABSTRACT F THE DISCLOSURE A process and apparatus for feeding a plurality of strands at constant speed through twister means having a plurality of guide assemblies spaced apart symmetrically about a circle and wherein the strands enter and leave the guide assemblies at equal angles.

This invention relates to a process and an apparatus for making twist crimped filaments.

`It is known to make twist crimped filament yarn by imparting a false twist to a running multifilament yarn threadline by rotating it in a false twisting device, and heat setting the twisted filaments so that when they pass out of the twisted zone they remain crimped. Por economic reasons high linear threadline speeds are preferred but these require high false twisting rotational speeds to insert the desired number of crimps per inch into the resultant filaments. It is known to operate such a false twist crimping process while drawing melt spun filament yarn, but the high false twist rotational speeds required place a relatively low practical limit on the linear drawing speed.

It is also known to make twist crimped filament yarns by processes in which there are no moving parts contacting the running threadline. In such methods two yarns are pretwisted around each other along part of their length and the yarns are then run as continuous threadlines through such pretwisted zone with twist damming means which completely prevent the predetermined dammed twist from bleeding along the running threadlines. In known processes using this method no high twisting speed is needed but it has been necessary to introduce means such as conical rollers to balance the tensions in the two dam twisted threadlines. Another disadvantage is that the filaments are less tightly crimped when two multifilament yarns are twisted around each other to a given number of turns per inch than when single filaments are similarly twisted around each other within one yarn.

We have now found that under certain conditions similar filamentary strands can be continuously twist crimped by a dammed twist process even at high speeds without the need for any mechanism to balance the tensions between such twisted strands so that the strands may conveniently be single filaments as well as multifilament yarns, and a multiplicity of fine strands may readily be dam twisted together.

According to this invention We provide a dammed twist process for making twist crimped filament yarns cornprising leading at equal speeds through a feeding device a plurality of filamentary strands which are not twisted around each other and each of which comprises at least one filament, and withdrawing such strands at equal speeds under at least some tension through a forwarding device, between which feeding and forwarding devices strands are pretwisted around each other by a fixed number of turns by mutual rotation between assemblies of guides, each individual guide in such assemblies guiding one strand, and each assembly having an axis of symmetry coincident with the axis of the twisted strands, such twist United States Patent O ice being heat set by heating and cooling such twisted strands between such assemblies of guides.

We prefer a process in which the angles of each individual strand through each individual guide in an assembly are equal.

We further prefer to use two mutually rotatable assemblies of guides contacting each mutually twisted group of strands.

The dammed twist crimping process of this invention may be integrated with drawing, in which case the for# warding device referred to hereinbefore is a draw roll. By drawing we mean the operation well known in the art of lconverting melt s-pun filaments into useful textile filaments by stretching them continuously to a ratio commensurate with their natural draw ratio. In such a process any known suitable drawing means may be used, for instance heated feed rolls, heated or unheated snubbing means or heating means which do not involve snubbing action. We prefer that at least part of the filament stretch involved in such drawing process takes place before the filaments reach the twisted zone. When the chosen drawing means includes a heated zone in an essentially straight length of threadline path after at least the first part of the draw, such heated zone may conveniently be used for fulfilling also the function of heat setting the dammed twist.

The twist crimping process of this invention may also directly follow drawing, in which case the feeding device referred to hereinbefore becomes the draw roll of a preceding drawing operation.

For smooth and fast operation untwisted filamentary strands are conveniently provided by feeding filaments continuously from a spinneret, without intermediate winding up and unwinding, into the process of this invention. When the process of this invention is not so integrated with spinning, single filament strands may be provided individually by side or over-end unwinding each from a separate bobbin or they may be provided in parallel bundles from one bobbiu which is side unwound so that no unwinding twist arises. Multifilament strands may be over-end unwoundeach from a separate bobbin, the slight unwinding twist of the filaments within the strands not significantly affecting the process of this invention provided that the strands are not twisted about each other before reaching the twisted zone between the feed and forwarding rolls.

According to another aspect of this invention we provide apparatus for making twist crimped filament yarns comprising, between feeding and forwarding means, assemblies of guides having a common axis of symmetry and mutually rotatable about an axis parallel to such axis of symmetry, means to cause and to prevent such mutual rotation, and between such assemblies heating and cooling means to set twist.

We prefer such assemblies to be in planes at right angles to such axes of symmetry and rotation.

We prefer the axes of symmetry and rotation to be coincident.

In one preferred form such apparatus is mounted on a known drawing machine such that the feeding means of the apparatus of this invention are the draw rolls of the drawing machine.

In another preferred form such apparatus is mounted on a drawing machine fitted with known means for drawing filamentary strands such that the feeding and forwarding means of the apparatus of this invention are the feed and draw rolls respectively of the draw frame, and known drawing means are provided before the first guide assem bly.

It will be clear that any known drawing means such as heating or snubbing devices may be used.

FIG. 1 is a schematic perspective view of an apparatus embodying the principles of the present invention;

FIG. 2 is an elevational view of one form of an orbital twister guide;

FIG. 3 is a sectional view taken on the line A-A of FIG. 3;

FIG. 4 is an elevational view of another form of an orbital twister guide;

FIG. 5 is a sectional view taken on the line X*X of FIG. 4; and

FIG. 6 is a schematic elevational view illustrating use of the orbital twister guide as a double guide.

One embodiment of the apparatus of this invention is illustrated in FIG. 1 of the accompanying drawings in which two multihole twist stop guides 31 and 32, the second of which may be rotated and clamped, are placed at each end of a zone 33 in which are a heated plate 34 and an unheated space 3S. The guides 31 and 32 are placed between a feed roll 36 and a draw roll 37 there being also a heated snubbing pin 38 between the feed roll 36 and the guide 31. In operation the strands 39 are passed through corresponding holes in guides 31 and 32 and then passed round the feed roll 36, round the snubbing pin 38 and round the draw roll 37. The guide 32 is then rotated through a predetermined number of turns and clamped. The strands are thereby twisted together between guides 31 and 32 as illustrated, the twisted filaments being heated by contact with the plate 34.

In this apparatus the filaments are drawn =by a conventional snubbng pin and plate tandem hot drawing process and they are simultaneously twist crimped according to the process of this invention while passing over the plate and through the cooling zone between the guides 31 and 32.

It will be appreciated that the guides 31 and 32 illustrated in FIG. l of the accompanying drawings are not very convenient in practical operation because of the necessity to string up the strands by passing their ends through holes in the guides before such strands are drawn in a continuous process Ibetween feed and draw rolls. It is most desirable to use threadable guides into which continuous strands can be inserted while being forwarded continuously.

According to a further aspect of this invention we therefore provide an improved multiple threadline guide particularly suitable for the dammed twist process of this invention comprising an assembly of threadable guides for individual strands symmetrically disposed about an axis of symmetry, rotatably mounted in bearings having a radius of a circle encompassing all such individual guides and such assembly being provided with means to cause and prevent such rotation. Such a multiple threadline guide is referred to hereinafter as an orbital twister guide. Preferably such individual guides are in a plane perpendicular to the axis of rotation and concentrically and equally spaced around such axis.

In a preferred form the orbital twister guide of this invention comprises a member rotatably mounted within bearings, in which member inwardly directed slots in a plane at right angles to the axis of rotation have inner closed ends symmetrically spaced about the axis of rotation within a radius smaller than the radius of such bearings, and outer open ends which are separately threadable through slots in the bearings at angular positions of such member in such bearings at which such slots in the member are inward extensions of such slots in such bearings.

In another preferred form the orbital twister guide of this invention comprises a member substantially as described hereinbefore, rotatably mounted in bearings, one part of which may be removed to permit removal and re-insertion of the disc and then reassembled.

One embodiment of the orbital twister guide of this invention is illustrated in FIGS. 2 and 3 of the accompanying drawings. Two plates 1 and 2 connected by spacing members 3 and 4 are pierced by circular holes 5,

each concentrically surrounded by recesses 6. The plates 1 and 2 are also pierced by slots 7 which penetrate through the recesses 6 to the holes 5. In the recesses 6 are nylon bearing inserts 8 split so as not to close slots 7. A gear wheel 9 is fixed between concentric annular projections 10, extending into the recesses 6 and seating in the nylon bearings 8. The gear 9 meshes with a pinion 11 rotatably mounted between the plates 1 and 2, on an aXle 12 extending through the plate 1 and attached to driving and clamping means not shown. The subassembly of gear wheel 9 and projections 10 is pierced by radial slots 13 each containing an inserted ceramic threadline guide 14, such guides 14 being arranged concentrically in the gear 9 on a circle with a diameter smaller than that of the holes 5.

In operation the gear 9 is rotated until a slot 13 is aligned with slots 7 and a iilamentary strand is inserted through such slots into a ceramic threadline guide 13. The gear is then rotated until another slot 13 is aligned with slots 7 and a second strand is similarly inserted. This procedure is repeated until all the strands required in a particular process are inserted each through a separate threadline guide 13. The gear 9 is then rapidly rotated by driving axle 12 by means not shown until a desired number of turns of twist has been imparted to the strands and then further rotation is prevented by clamping axle 12 by means not shown. During this twisting operation the strands are twisted between a twist stop and the orbital guide which when clamped acts as the second twist stop. We prefer to use for the first twist stop either another similar orbital twisters guide or a slotted guiding member similar to that in the orbital twister guide but not rotatably mounted.

Another embodiment of the orbital twister guide is illustrated in FIGS. 4 and 5 of the accompanying drawings. A subassembly of gear wheel 20 and projections 21 similar to members 9 and 10 of FIG. 2 is provided with guides 22 similar to the guides 13 of FIG. 2 but spaced so as to correspond conveniently with the spacing of spinneret holes through which the lilaments to be crimped are extruded. Two pairs of housing plates 23 and 24 and 25 and 26 are connected respectively by spacing members 27 and 28 and are clamped together by means not shown along the line XX.

In operation the housing subassembly 23, 24 and 27 is removed, the guide subassembly 20 and 21 is extracted, and held under a spinneret from which emerge the laments to lbe treated by the process of this invention. One monolament or multilament strand is passed through each guide slot, the guide subassembly is re-inserted in the housing plates 2S and 26 and the housing plates 23 and 24 are replaced and clamped along line XX. A twist stop guide which may be a similar orbital twister guide is strung up similarly. The guides are positioned at each end of a heating zone provided between feed and draw rolls and the strands are then strung up over such feed and draw rolls. Finally, the orbital twister guide is rotated to provide the required twist in the running threadline.

The orbital twister guide of this invention is conveniently provided also as a double guide as shown schematically in FIG. 6 of the accompanying drawings. Two twisted threadlines are run in parallel through such a guide which provides S twist in the right-hand threadline and Z twist in the left-hand threadline when rotated as shown, so that the threadlines may conveniently be plied after twist crimping to provide a torque free crimped filament yarn.

The following examples illustrate our invention:

EXAMPLE 1 A melt spun twistless yarn of polyethylene terephthalate consisting of 15 filaments each of 18 denier and having an intrinsic viscosity measured in orthochlorophenol at 20 C. of 0.65 and a birefringence of 0.008 was side unwound from a bobbin and the filaments were threaded individually through a set of 15 concentric equally spaced holes each 0.03 diameter on a circle of 0.75" diameter in a steel disc of 1 diameter. The filaments were similarly threaded through three other similar discs which were then mounted in clamps, the first between the bobbin and the feed roll of a drawframe, the second `'between a heated snubbing pin and a heated plate placed between the feed roll and draw roll of the drawframe, the third after the plate and the fourth before the draw roll. The discs were disposed so that the separately guided filaments passed from `the rst to the fourth disc without twist. The snubbing pin had a diameter of 2" and was heated to 95 C., the plate was 8" long and heated to 200 C. and the third disc was placed 4" from the end of the plate. The yarn was passed round the feed roll rotating at a surface speed of 25 r.p.m., round the snubbing pin and over the draw roll which was rotated at 100 r.p.m. The third disc was then rotated and reclamped when a twist level of 70 turns per inch had been built up between the second and third discs and the heated plate was brought into contact with this dam twisted part of the threadline. A drawn and bulked torque yarn with highly crimped filaments was produced.

EXAMPLE 2 Two spun yarns of polyhexamethylene adipamide each containing two 35-denier filaments with a birefringence of 0.005 and a relative viscosity of measured at 8.4%

concentration in 90% formic acid at 25 C. were side unwound from bobbins and drawn to a ratio of 5.5 at 1,000 ft. per minute on a draw frame comprising feed rolls heated to 95 C., a 12'l long plate heated to 230 C. and cold draw rolls. Two double orbital twister guides as illustrated in FIG. 6 of the accompanying drawings were placed one between the hot feed roll and the hot plate and the other between the hot plate and the draw roll. A 6 gap was left between the hot plate and the second orbital twister guide, in which gap a draught of cooling air was directed on to the threadline. The two filaments of each yarn were each slotted into two diametrically opposed guides in one of the rotors of each double orbital twister guide. The second guide was then rotated at 1100 r.p.m. until 120 turns per inch of twist had been built up in the threadlines over the heated plate, being S twist in one threadline and Z twist in the other. The orbital twister guide was then held stationary and the two threadlines were plied at the draw roll and wound up to give a highly crimped balanced torque yarn.

EXAMPLE 3 Two 79-denier monolaments of polyhexamethylene adipamide with a birefringence of 0.0009 and a relative viscosity of 35 measured as in Example 2 were over end unwound from bobbins and processed as described in Example 2 but using single orbital twister guides as illustrated in FIGS. 2 and 3 of the accompanying drawings and using various draw ratios between 3.0 and 6.0. Using a tension meter in the cooling zone of the twisted threadline it was found that the maximum number of twists per inch that could. be inserted without breaking the running threadline was achieved at an optimum tension in the twisted region of between 1.5 and 2 gms. per denier, corresponding to draw ratios between 4.6 and 5.4, within which range of a highly crimped drawn yarnwas produced with a tenacity of about 3.5 grams per denier.

EXAMPLE 4 Three 12S-denier yarns of polyethylene terephthalate each containing 20 .filaments with a birefringence of 0.008 and an intrinsic viscosity measured in orthochlorophenol at 20 C. of 0.65 were over end unwound and drawn to a ratio of 3.86 using the drawing process described in Example 2 but with the hot plate at 215 C'. The three yarns were slotted symmetrically Yinto single 6 orbital twister guides as illustrated in FIGS. 2 and 3 of the accompanying drawings placed respectively after the hot feed roll and after the hot plate. A dam twist of 25 turns per inch was inserted over the hot plate by rotating the orbital twister guide at 1100 r.p.m.' and the guide was then clamped. The yarns were plied together after the draw roll to give a drawn crimped 3-ply torque yarn.

EXAMPLE 5 Three `filaments of polyethylene terephthalate extruded at 290 C. were sep-arated below the spinneret by a ceramio guide in the form of a comb before passing them round a heated feed roll at C. and a cold draw roll providing a draw ratio of 3.83 at a final windup speed of 8,000 feet per minute at which the filament denier was l5. The three filaments were symmetrically slotted into two orbital twister guides of the type illustrated in FIGS. 2 and 3 of the accompanying drawings placed between the feed and draw rolls, and between the guides the lilaments traversed a 2 ft. long grooved hot plate at 230 C. followed by a 1 ft. cooling zone across which a draught of cooling air was provided. The second orbital twister guide `was rotated at 1100 r.p.m. until a twist of 50 turns per inch had been established in the groove of the hot plate. The guide was then clamped. This integrated spinning, drawing and textured process provided a three-filament bulked torque yarn.

EXAMPLE 6` Two S05-denier spun yarns of polyethylene terephthalate each containing 8 filaments with a birefringence of 0.008 and an intrinsic viscosity of 0.65 determined in a 1% solution of orthochlorophenol at 20 C. were drawn separately at a draw ratio of 3.4 over a hot feed roll (90 C.) and a hot plate (200 C.) at 2000 ft./min. finishing with a yarn twist of 1/2 turn per inch. The two yarns were slotted symmetrically into two single orbital twister guides as illustrated in FIGS. 2 and 3 of the accompanying drawings placed between two rolls, both rotating at surface speeds of 400 ft./min., one guide being placed between the -first roll and a 2 ft. grooved hot plate C.) and the other between a cooling draught of air immediately after the hot plate and the second roll. The two yarns coming from the second roll were then passed through a 2 ft. hot air tube (air circulating in the same direction as the yarn at 230 C., l5 p.s.i.) to a third roll rotating at 200 ft./min.

A dam twist of 60 t.p.i. was inserted on the running threadline over the hot plate by rotating the orbital twister guide at 1100 r.p.m. and the guide was then clamped. The yarns coming from the third roll were plied giving a stabilised crimped yarn of low torque.

It will be appreciated that although the process and apparatus of this invention may be used with any number of strands drawn at any speed at which winding means are available, it is particularly useful in connection with a multiplicity of fine strands drawn at high speeds as encountered in integrated spin draw processes.

What I claim is:

1. A process for making twist crimped filament yarns comprising:

leading at equal and controlled speeds through a feeding device a plurality of filamentary strands which are not twisted around each other and each of which comprises at least one filament; and withdrawing such strands at equal and controlled speeds under at least some tension through a forwarding device, between which feeding and forwarding devices such strands are pretwisted around each other by a fixed number of turns by mutual rotation between assemblies of guides, each strand passing through one guide of each such assembly, each assembly being symmetrically spaced around a circle in a plane at right angles to the twisted length of strands and having a common axis of symmetry, and the strands being deflected through substantially equal angles by each guide of an assembly, such twist being set by heating and cooling between such assemblies of guides.

2. A process according to claim 1 in which melt spun filaments are drawn between the feeding and forwarding devices and at least part of the draw takes place before the twisted zone.

3. A process according to claim 1 in which one group of strands is twist crimped in S configuration and another group of strands is twist crimped in Z configuration and such groups of twist crimped strands are combined to provide a balanced torque yarn.

4. Twist crimped yarns made according to the process of claim 1.

5. Balanced torque twist crimped yarns made according the the process of claim 3.

6. Apparatus for making twist crimped filament yarns comprising:

constant speed feed means for feeding a plurality of rIilamentary strands; constant speed withdrawing means for withdrawing the strands at constant and equal speeds under at least some tension; twisting means disposed between said feed and said withdrawing means, said twisting means including at least two spaced apart guide assemblies each symmetrically spaced around a circle in a plane at right angles to the strands and having a common axis of symmetry, each assembly having a plurality of guide passages through each of which a different strand passes, the strands being deected through substantially equal angles by the passages, at least one of said guide assemblies being rotatable relative to another assembly about its axis to any of a plurality of several fixed positions whereby rotation of said one assembly to a preselected position causes the strands to be twisted as they are drawn through the guide passages of the assemblies; and heating and cooling means between adjacent assemblies to set twist in the strands. 7. Apparatus as in claim 6 in which the withdrawing means includes draw rolls.

8. Apparatus as in claim 7 in which the feed means includes feed rolls.

References Cited UNITED STATES PATENTS 1,302,187 4/1919I Lipps 57-77.3 2,807,130 9/1957 Trapido et al 57-77.3 2,981,050 4/1961 Dewhirst 57-77.45X 3,018,609 l/1962 Maier et al 57-l57 3,355,872 12/1967 Gilerist et al. 57-34X 3,362,147 l/l968 Curtis 57-34 3,408,807 11/1968 Sylthe 57-12X 3,412,543 11/1968 Horvath 57-34 DONALD E. WATKINS, Primary Examiner 

